server-side-rendering

A slow First Contentful Paint and poor SEO occur because client-only React rendering makes search engines wait for JavaScript execution to see content. Server-side rendering solves this by generating complete HTML on the server for each incoming request, delivering crawlable content immediately.

To generate per-request dynamic HTML in React, use an SSR-capable framework like Next.js to fetch request-time data on the server, produce HTML reflecting the current request context, then hydrate the markup on the client for interactive UI.

Client-side hydration is the process of attaching event listeners and interactive state to server-generated HTML. You need hydration after server-side rendering to make the static markup returned to the browser fully interactive as a React application.

Yes, server-side rendering works with Next.js for content-heavy pages by generating fully formed HTML on each request. This provides users with immediately visible header and article content while the server handles data fetching before sending ready-to-display markup.

You should not use server-side rendering when your React application requires no per-request data fetching, has minimal SEO requirements, or serves highly interactive pages where the overhead of server HTML generation and client hydration outweighs the initial paint benefits.

The best way to improve SEO for a content-heavy React application is server-side rendering, which provides search engines with crawlable, fully formed HTML instead of relying on client-only rendering that delays content visibility.